1. Field of the Invention
The invention relates to an impact generator for rotating a weight by means of a rotary member and striking a struck member with the weight, thereby continuously generating impact force for working.
2. Description of the Related Art
An impact generator is a device for continuously generating impact, force (shock force). Such impact generator may be applied to a crusher for crushing concrete or hardened asphalt in a road construction, a building site and the like, a reaper for cutting off fruit and branches of plants, and a root cutter for cutting off roots of plants and the like, for example.
By way of example, Japanese Laid-Open Patent Publication No. Hei 7-95827 has disclosed an impact generator according to the prior art. FIG. 10A is a transverse sectional view showing the impact generator D100 according to the prior art and FIG. 10B is a longitudinal sectional view showing the impact generator D100. The impact generator D100 is applied to a reaper and serves to give continuous impact force to a cutting blade 191. The impact generator D100 converts rotating force transmitted from a power unit such as an engine into reciprocating impact force and transmits the reciprocating impact force to the cutting blade 191.
As shown in FIGS. 10A and 10B the impact generator D100 comprises a rotary member 110 and a weight 130. The rotary member 110 is rotatably supported in a casing 150 by means of rotary shafts 111 and 112. The rotary member 110 has plate-shaped holding portions 113 and 114. The plate-shaped holding portions 113 and 114 are connected to each other through a connecting shaft portion 115. The connecting shaft portion 115 is positioned eccentrically from the center C100 of rotation of the rotary member 110. Circular holes 113a and 114a are formed on the plate-shaped holding portions 113 and 114, respectively. A cylindrical weight 130 is held in the holes 113a and 114a. The holes 113a and 114a have diameters which are larger than the diameter of the weight 130. Therefore, the weight 130 can freely move to some extent in the holes 113a and 114a. More specifically, the weight 130 is movably held by the rotary member 110.
When the weight 130 performs a circular motion around the rotary shafts 111 and 112 of the rotary member 110 by the rotation of the rotary member 110, the top of a tappet 192 positioned to interfere with the locus of the circular motion is struck with the weight 130. The tappet 192 is supported movably in an axial direction thereof (in a transverse direction in FIGS. 10A and 10B). Therefore, the tappet 192 is struck, thereby giving an impact to the cutting blade 191 positioned on the left of the tappet 192 in FIGS. 10A and 10B. Thus, when the rotary member 110 is rotated, continuous impact force is given to the cutting blade 191.
Disk-shaped plates 165 and 166 are provided in the casing 150. The plates 165 and 166 are provided in contact with upper and lower end faces of the weight 130, thereby regulating a vertical position of the weight 130 which performs the circular motion.
In the impact generator D100 described above, the tappet 192 is repeatedly struck with the weight 130. Accordingly, if the lubrication of contact faces of the weight 130 and the tappet 192 is not well maintained, the contact faces are greatly worn. In order to keep the lubrication of the contact faces well maintained, it is preferable that a grease should be caused to adhere to the contact faces. Moreover, the weight 130 is caused to slide on the internal wall surfaces of the holes 113a and 114a of the rotary member 110. In order to keep the slide on such wall surfaces well maintained, it is preferable that the grease should be caused to adhere to the weight 130 and the rotary member 110. Furthermore, the weight 130 performs a circular motion while coming in contact with the plates 165 and 166 for regulating the vertical position thereof. Therefore, it is necessary to keep the lubrication well maintained here as well by causing the grease to adhere to portions between the weight 130 and the plates 165 and 166.
However, when the rotary member 110 is rotated, the grease receives centrifugal force and gradually moves away from the center C100 of rotation of the rotary member 110. Therefore, the grease starts to keep away from the surfaces of the rotary member 110 and the weight 130 and to be collected on an inner peripheral wall surface 159 of the casing 150. Consequently, the lubrication on the contact faces of the weight 130 and the tappet 192 becomes poor. Thus, the contact faces are greatly worn. Moreover, insufficient lubrication is caused between the weight 130 and the rotary member 110, the plate 165 and the like.
In consideration of above-mentioned circumstance, it is an object of the invention to provide an impact generator capable of keeping good lubrication of a weight and other members which come in contact with the weight.
In order to solve the above-mentioned problems, the invention provides an impact generator comprising a rotary member for being rotated upon receipt of rotating force, a weight movably held by the rotary member for striking a struck member, and an impregnating member capable of impregnating a grease, wherein the impregnating member is extended from a vicinity of an inner peripheral wall surface of a chamber for accommodating the rotary member and the weight to a position where the impregnating member comes in contact with the weight performing a circular motion.
According to the impact generator described above, the grease reaching the inner peripheral wall surface of the chamber by centrifugal force is absorbed in the impregnating member. The weight comes in contact with the impregnating member while performing the circular motion. Therefore, the grease absorbed in the impregnating member adheres to the surface of the weight. Accordingly, the lubrication of the weight and other members which come in contact with the weight can always be kept well maintained.
In the above-mentioned impact generator, if the impregnating member is constituted to come in contact with a portion of the weight""s face which abuts against the struck member, the grease supplied from the impregnating member can directly be applied to the face of the weight which abuts against the struck member.
In the above-mentioned impact generator, the impregnating member may be formed of any material which can impregnate the grease. For example, the impregnating member may be formed of felt.
In order to solve the above-mentioned problem, furthermore, the invention provides another impact generator comprising a rotary member for being rotated upon receipt of rotating force, a weight movably held by the rotary member for striking a struck member, gears for transmitting the rotating force from a power unit to the rotary member, a casing for accommodating the rotary member, the weight and the gears, and a separating plate for separating an internal space of the casing into a first chamber for accommodating the rotary member and the weight and a second chamber for accommodating the gears, and coming in contact with the weight to regulate a position of the weight, wherein at least one communicating portion for causing the first chamber to communicate with the second chamber is formed on the separating plate.
According to the impact generator described above, if the grease is put in the second chamber, it can move to the first chamber through the communicating portion. Accordingly, a surface of the weight in the first chamber can always be kept in a state in which the grease adheres thereto. Thus, the lubrication of the weight and other members which come in contact with the weight can always be kept well maintained.
In the above-mentioned impact generator, if the communicating portion is included in or interferes with a portion of the separating plate""s face with which the weight comes in contact, the grease passing through the communicating hole first adheres to the weight and then enters a clearance between the weight and the separating plate. Accordingly, the lubrication of the weight and the separating plate can particularly be kept well maintained.
In the above-mentioned impact generator, the communicating portion for causing the first chamber to communicate with the second chamber-can be formed in any way. For example, the communicating portion may be a hole.
These objects as well as other objects, features and advantages of the invention will become more apparent to those skilled in the art from the following description with reference to the accompanying drawings.